Swift - If-else Statement

Swift - If-else Statement

The if-else statement in Swift is a fundamental control flow structure that allows code to execute based on whether a specific condition is true or false.

Syntax:

The general structure of an if-else statement is as follows:

if condition { // Code to execute if the condition is true } else { // Code to execute if the condition is false }

Example:

Let's consider a simple example where we check if a number is even or odd:

let number = 5 if number % 2 == 0 { print("The number is even.") } else { print("The number is odd.") } // Output: The number is odd.

In this example:

  • The if condition checks if the remainder of the number divided by 2 is zero (meaning the number is even).
  • If the condition is true, it prints "The number is even."
  • If the condition is false (as is the case with the number 5), the code inside the else block executes, printing "The number is odd."

Notes:

  • The else block is optional. You can have an if statement without an else:
if condition { // Code to execute if the condition is true }

  • Parentheses () around conditions are optional in Swift. So, both if condition {...} and if (condition) {...} are valid, but the former is more idiomatic in Swift.

  • Always ensure that the condition inside the if statement returns a boolean (true or false). If it doesn't, the Swift compiler will raise an error.

  • The if-else statement can be expanded further using else if to check for multiple conditions, which was discussed in the previous answer on the if-else-if statement.

Examples

  1. How to use if-else in Swift programming:

    • Description: The if-else statement in Swift allows you to conditionally execute code blocks based on a given condition.

    • Code:

      let number = 10 if number > 0 { print("Number is positive") } else { print("Number is non-positive") }

  2. Conditional statements in Swift with if-else:

    • Description: if-else is a fundamental conditional statement in Swift, allowing you to handle alternative code paths.

    • Code:

      let temperature = 25 if temperature > 30 { print("It's hot!") } else { print("It's not too hot.") }

  3. Handling multiple conditions in if-else in Swift:

    • Description: Multiple conditions can be handled using chained if-else statements.

    • Code:

      let grade = 85 if grade >= 90 { print("A") } else if grade >= 80 { print("B") } else { print("C or below") }

  4. Nested if-else statements in Swift:

    • Description: if-else statements can be nested to handle more complex conditions.

    • Code:

      let age = 25 if age >= 18 { print("You are an adult") if age >= 21 { print("You can buy alcohol") } } else { print("You are a minor") }

  5. Using logical operators in Swift if-else:

    • Description: Logical operators (&&, ||, !) can be used to combine conditions in if-else statements.

    • Code:

      let isWeekend = true let hasPartyInvitation = false if isWeekend || hasPartyInvitation { print("Let's party!") } else { print("No party today.") }

  6. Swift if-else statement with optionals:

    • Description: Optionals can be safely unwrapped using if-else statements with optional binding (if let or guard let).

    • Code:

      let optionalValue: Int? = 42 if let unwrappedValue = optionalValue { print("Optional has a value: \(unwrappedValue)") } else { print("Optional is nil") }

  7. Conditional expressions and ternary operator in Swift:

    • Description: Ternary conditional operator (a ? b : c) provides a concise way to express if-else conditions.

    • Code:

      let isSunny = true let weatherMessage = isSunny ? "It's sunny!" : "It's not sunny." print(weatherMessage)

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